Possibly Corrupt Catalog .Dat Files - A Serious Problem?

Question

This question continues from http://forums.adobe.com/thread/804620?tstart=-1.
The three .dat files (backupCt.dat, collstatus.dat and tagstatus.dat) in one of our Adobe\Catalog Folders subfolders ("Paintings") may be corrupted.  Whereas these files appear to be rewritten routinely, along with the thumb.5.cache file, each time Adobe Photoshop Elements is opened to one or another of our catalogs, the three files have not been rewritten for the Paintings catalog since 3/9/11, although that catalog has been opened almost every day.  This situation came to my attention because the three files showed up in error messages in the Second Copy backup program I run every night, saying that the three files could not be copied because access is denied.  In my previous post (referenced above), MichelBParis suggested that I could delete those files safely and that they would be rewritten when the catalog was next opened.  However, I can't delete the files, rename them, or move them elsewhere because of the access denied status (I get an error message asking me to be sure that the disk is not full or write protected [which it is not] and that the files are not currently in use [which they are not, at least as far as I can tell -- Adobe Photoshop Elements has been closed when I have attempted all procedures, and I don't see any other applications or processes running, as per Task Manager, that I can immediately identify as belonging to Adobe).  I have thought about restarting the computer in Safe Mode to see if I can delete the files then.  However, I am a bit nervous about trying this, as the Paintings catalog in question is huge and of enormous importance to my wife -- I don't want to do something that might inadvertently make it impossible to access or use that catalog (as happened to us once before when we were using Adobe Photoshop Album Starter Edition 3.2, and the catalog became corrupted).
My questions:
(1)  Does anyone know what these three .dat files actually do?  I've not so far been able to find this information via Google.
(2)  If these files remain in their present state (access denied and non-rewritten), do we run the risk of ending up with a serious problem down the road and loss of our ability to access the catalog (or some other loss of functionality)?
(3)  Would it be safe for me in fact to delete these three files if I can find a way to do so (e.g., in Safe Mode)?
(4)  If it would, indeed, be safe for me to delete the files, and if that would seem to be a next step to try, are there any suggestions for how I could go about doing so?
(5)  Any other suggestions about how I can get the Paintings catalog back in proper shape?
Thanks for any help anyone can provide!

Answer 1

Most likely the files are not corrupt if your basis is that the backup program cannot open the files.  However, I would be concerned about the security settings in the files if multiple users need to access the same catalog.  This might be why you aren't seeing any changes to the time/date because one of the user doesn't have rights to modify the file.
Please tell me what OS you are running and what version of PsE?
For PsE 9 (and I think 8), you can modify the media-analysis options from the Organizer...
Menu 'Edit->Preferences->Media-Analysis'
Uncheck either checkbox as shown in the red circles
After hitting 'OK', exit the organzier and reboot.
See if you can access the .Dat files.
Instead of copying the catalog, I would just create a new empty catalog.  This can be done as follows...
Menu 'File->Catalog...'
Make sure you note where the current catalog is located before you continue.  The name of the current catalog is found in the box at the bottom of the dialog with [Current] added to the end of the name.  Now...
Click on 'New...'
Enter the new catalog name.
Click on 'OK'
The organizer will use the new catalog.  You will now see nothing is in the organzier.
See if you can access the .dat files.  You may need to reboot.
You can select the previous catalog as follows...
Menu 'File->Catalog...'
Click on the previous catalog name
Click 'Open'
There is something not right with the security settings especially if you want multiple users to be able and access the catalog.  As far as how things got messed up -- I have no idea.  Some possible options are that one user has more rights than another user.  The one with more rights created the files just fine but the other user has no way to read the files.  Or someone was messing with the security settings.
Security settings in Windows can get very complex very fast. I hesitate attempting to walk through this can be done because there could be many factors which has caused this issue.  You could have specific security settings on the files which override parent directory security settings.   Or the parent directory security setting could simply be wrong.
You first need to determine if both users need write access to the catalog.  If this is the case and they are not administrators, I would go ahead and set the security settings on the folder containing the catalog.  You do need to be careful so you don't remove security settings such that you cannot even make changes to the security settings.  Make sure you give full control to "This folder, subfolders, and files" in the Permission Entry dialog.
I would encourage you to look at the effective permissions on all files in the catalog after making any changes and before you start up PsE again.  I have no idea what would happen if the security setting was wrong on a single file.  This could cause a corrupted catalog depending on how PsE is written.